A method and apparatus for grayscale adjustment are provided. The method includes steps of: obtaining pixel grayscale values or at least one region grayscale value of an original image; selecting a predetermined grayscale compensation interval, from multiple predetermined grayscale compensation intervals, which corresponds to the pixel grayscale values or the region grayscale value as a ready-to-use grayscale compensation interval; obtaining a grayscale compensation value which corresponds to the ready-to-use grayscale compensation interval; and performing compensation on pixel grayscale values of the original image according to the grayscale compensation value.